Glaucoma is a degenerative disease of the eye wherein the intraocular pressure is too high to permit normal eye function. As a result, damage may occur to the optic nerve head and result in irreversible loss of visual function. If untreated, glaucoma may eventually lead to blindness. Ocular hypertension, i.e., the condition of elevated intraocular pressure without optic nerve head damage or characteristic glaucomatous visual field defects, is now believed by the majority of opthalmologists to represent merely the earliest phase in the onset of glaucoma.
There are several therapies for treating glaucoma and elevated intraocular pressure, but the efficacy and the side effect profiles of these agents are not ideal. Recently potassium channel blockers were found to reduce intraocular pressure in the eye and therefore provide yet one more approach to the treatment of ocular hypertension and the degenerative ocular conditions related thereto. Blockage of potassium channels can diminish fluid secretion, and under some circumstances, increase smooth muscle contraction and would be expected to lower IOP and have neuroprotective effects in the eye. (see U.S. Pat. Nos. 5,573,758 and 5,925,342; Moore, et al., Invest. Opthalmol. Vis. Sci 38, 1997; WO 89/10757, WO 94/28900, and WO 96/33719).
Some Maxi-K channel blockers containing ketone functional groups have quite low aqueous solubility. This presents a serious problem when used to treat ocular diseases such as glaucoma because treatment is typically in the form of aqueous ophthalmic solution formulations.